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From "Jonathan Ellis (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (CASSANDRA-6179) "Load" calculated in "nodetool info" is strange/inaccurate in JBOD setups
Date Tue, 22 Oct 2013 23:20:42 GMT

    [ https://issues.apache.org/jira/browse/CASSANDRA-6179?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13802406#comment-13802406
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Jonathan Ellis commented on CASSANDRA-6179:
-------------------------------------------

CASSANDRA-6231.

> "Load" calculated in "nodetool info" is strange/inaccurate in JBOD setups
> -------------------------------------------------------------------------
>
>                 Key: CASSANDRA-6179
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-6179
>             Project: Cassandra
>          Issue Type: Bug
>         Environment: JBOD layouts
>            Reporter: J. Ryan Earl
>         Attachments: dump.txt
>
>
> We recently noticed that the storage capacity on Cassandra nodes using JBOD layout was
returning what looks close to the average data volume size, instead of the sum of all JBOD
data volumes.  It's not exactly an average and I haven't had time to dig into the code to
see what it's really doing, it's like some sort of sample of the JBOD volumes sizes.
> So looking at the JBOD volumes we see:
> {noformat}
> [jre@cassandra2 ~]$ df -h
> Filesystem            Size  Used Avail Use% Mounted on
> [...]
> /dev/sdc1             1.1T  9.4G  1.1T   1% /data/1
> /dev/sdd1             1.1T  9.2G  1.1T   1% /data/2
> /dev/sde1             1.1T   11G  1.1T   1% /data/3
> /dev/sdf1             1.1T   11G  1.1T   1% /data/4
> /dev/sdg1             1.1T  9.2G  1.1T   1% /data/5
> /dev/sdh1             1.1T   11G  1.1T   1% /data/6
> /dev/sdi1             1.1T  9.8G  1.1T   1% /data/7
> {noformat}
> Looking at 'nodetool info' we see:
> {noformat}
> [jre@cassandra2 ~]$ nodetool info
> Token            : (invoke with -T/--tokens to see all 256 tokens)
> ID               : 631f0be3-ce52-4eb9-b48b-069fbfdf0a97
> Gossip active    : true
> Thrift active    : true
> Native Transport active: true
> Load             : 10.57 GB
> {noformat}
> So there are 7 disks in a JBOD configuration in this example, the sum should be closer
to 70G for each node.  Maybe we're misinterpreting what this value should be, but things like
OpsCenter appear to use this "load" value as the size of data on the local node, which I expect
to be the sum of JBOD volumes.



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